Position-retaining device



April 19, 1966 J. E. MARTENS ETAL 3,246,868

POSITION-RETAINING DEVICE Original Filed June 17, 1963 2 Sheets-Sheet 1 INVENTORS JACK E. MARTENS m I 1 3 BY WILLIAM L. ASZMAN ATTORN EYS April 19, 1966 J. E. MARTENS ETAL 3,246,868

POSITION-RETAINING DEVICE Original Filed June 17, 1963 2 Sheets-Sheet z INVENTORS JACK E. MARTENS BY WILLIAM L.ASZMAN m MML ATTORN EYS United States Patent 3,246,868 POSITION-RETAINING DEVICE Jack E. Martens, Bloomfield Hills, Mich., and William L.

This application is a continuation of our application Serial No. 288,176, filed June 17, 1963.

This invention relates to a position-retaining device and more particularly is directed to a linear extensible holding mechanism for a movable chair back or contour bed.

An object of this invention is to provide an improved position-retaining device.

Another object of this invention is to provide an improved position-retaining device capable of fixedly holding in either axial direction.

Another object of this invention is to provide an improved position-retaining device with control mechanism permitting release from holding engagement.

Other objects and advantages of this invention will become apparent after the following description hereinafter set forth is considered in conjunction with the drawings annexed hereto.

In the drawings:

FIGURE 1. is a diagrammatic side view of a bed employing the present type of position-retaining device;

FIGURE 2 is a side view of the position-retaining device, partly in section;

FIGURE 3 is a plan view of a cover for the positionretaining device with a cut-away showing control mechanism;

FIGURE 4 is a plan view of one end of the position-retaining device of FIGURE 2;

FIGURE 5 is a side view of the cover shown in FIG- URE 3;

FIGURE 6 is an isometric view of one end of the position-retaining device; I

FIGURE 7 is an isometric view similar to FIGURE 6 but showing certain elements in a different position; and

FIGURE 8 is a detail view of one element of the invention.

The position-retaining device of the type to be disclosed herein has utility in a bed (FIGURE 1), a chair having a positionable b ack or in other mechanism wherein it is desired to fixedly retain two movable body members relative to each other. In FIGURE 1, for example, when the position-holding device 10 is locked at a predetermined extension, movable portions of the bed remain relatively fixed. This position-retaining device has utility in the settings of US. Patent Nos. 2,579,305 and 3,G46,055.

FIGURE 2 shows the linearly extensible position-holding device 10 in retracted position. The device includes an outer section, casing or tubular member 12 having pins or projections 14 adapted for connection to a body member and a telescopically received member 16 having an aperture 18 at its outer end 19 for connection with a second body member relatively movable with respect to the other body member. Whenever internal mechanism of the position-holding device locks outer casing 12 and extensible section or member 16 in axial restraint, the body members, to which they are respectively attached, are held in relative fixed position.

Outer casing 212 is generally tubular in form. A peripheral portion 20 thereof near one end is removed and slots 22, '22 are provided adjacent opposite ends for a purpose to be fully explained hereinafter. The other end of casing 12 is inturned and provided with an annular plastic sleeve 24 for slidably receiving extensible member 16. A thrust-bearing block 30 is fixedly secured on the inside of casing 12 near opening 20. The block is provided with an axial opening for the purpose of receiving therethrough a portion of rotatable rod, screw or threaded part 34. Relatively steep helical threading 36 is provided over a substantial portion of the screw and terminates in an axial shoulder 38 adjacent an unthreaded portion (not shown). A brake dru-m 40 is fixedly carried on the inner extremity of the unthre-aded portion of screw 34 for co-rotation therewith within casing 12 adjacent opening 20.

Thrust bearings 42 and 42' are received adjacent shoulder 38 and drum 40 for prevent-ing axial movement of the screw with respect to thrust block 30. Screw 34 is rotatably supported within the block, but is axially restrained thereby.

Extensible member 16, also tubular in form, is coaxially and telescopically received within outer casing 12 for movement between retracted and extended positions. The inner end 26 of extensible member 16 surrounds a nut 28. The shell of member 16 is staked on opposite sides 50, 52 of nut or threaded part 28 for fixedly retaining the nut therein. Nut 28 is provided with rela tively steep helical threading for cooperation with threading 36 on screw 34.

Casing 12 and 16 are so mounted on the movable body members to prevent rotation about their axes during reciprocable movement therebetween. As previously mentioned, the helical threading on nut 28 and screw 34 is relatively steep. It is obvious, since screw 34 is rotatably mounted within casing 12, that axial thrust applied between respective pins 14 and aperture 13, causes screw 34 to rotate as nut 28 is moved to a new position thereon.

Structure will now be described which locks and selectively unlocks screw 34 from rotation. A coil spring brake or lock 54 is disposed around drum 40 for selectively holding the drum and screw against rotation. The coil preferably has a plurality of helical turns wound to an inside diameter normally slightly less than the diameter of drum 40. Coil 54 must necessarily be expanded to be received over drum 40, and once thereon, radially grips its surface in holding engagement. FIG- URE 2 discloses coil 54 as right-hand wound, but it may be left hand as well since its function is to grip drum 40 against rotation in either direction. The coil wire cross section is shown to be substantially square with a flat surface thereof defining the inside diameter which faces drum 40. Other cross-sectional wire configurations may be used, but advantage has been found in providing a bro-ad surface on the coil adjacent the drum. Opposite ends of coil 54 terminates in tangs 56, 58 which extend substantially radially from one side thereof. When the coil is in position on drum 40, tangs 56, 58 project through slot 22 on casing 12 and are disposed adjacent opposite side walls or stops 23 and 25 respectively. This is clearly shown in FIGURES 6 and 7. The tangs are out of axial alignment by approximately 5 to 10 degrees. It is clearly shown in FIGURE 6 that the back portion of tangs 56, 58 are disposed adjacent walls 23, 25, respectively, of slot 22. A slight space is provided between the tangs and the walls to permit the tangs to be moved apart so as to expand the inside diameter of coil 54 out of gripping contact with drum 40. The details of a mechanism for expanding coil 54 will be discussed later in this specification.

It is readily apparent from FIGURES 2, 6 and 7 that when a force attempts to extend or retract casing 16 with respect to casing 12, it will be permitted to do so whenever screw 34 is freely rotatable. Axial pressure applied by nut 28 on steep helical threads 36 tends to cause rotation of screw 34, but once the screw is locked from rotation, nu-t 28 is prevented from further axial movement in either direction. Therefore, the lineardistance between pins 14 on casing 12 and aperture 18 of casing 16 is fixed for maintaining a seat back or the like in a selected position.

' Threading 36 may be either right or left hand because coil brake 54 is adapted to hold drum 40 from rotation in either direction.

Sincecoil 54 engages drum 40 with an initial frictional grip, a force in either axial direction by nut 28 tends to rotate screw 34, drum 40 and coil tangs 56 or 58 within slot 22. Once either tang is brought into contact with a respective wall, further rotation by the drum is resisted byincreased gripping action by the coil brake. Once a tang 56 or 58 has been moved into contact with an adjacent wall, braking action is commenced; and further efiorts to rotate screw 34 are increasingly resisted by coil 54 which progressively grips drum 40. It is apparent, therefore, that rotation of drum 4%} in either direction is resisted by coil brake 5.4. In other words, rotation of the drum tends to wrap the coil about it. As clearly shown in FIGURES 6 and 7, a small amount of play or movement of tangs 56, 58 are permitted between the walls of slot 32. These few degrees of play are not objectionable in the adjustor, and it does provide for cooperation with a release mechanism to be more fully described. FIGURE 2 discloses right-hand threaded screw; and, therefore, a compressive load carried by the device between pins 14 and aperture 18 tends to rotate drum 40- clockwise as viewed from the left end. Conversely, an extensive load between pins 14 and aperture 18 tends to rotate drum 4% in a counterclockwise direction. The effect of a load in tension, causing the counterclockwise rotation of drum 40, brings tang 58 into contact with wall and moves tang 56 away from wall 23. This is shown in FIGURE 6. A reversal of the load direction to compression causes clockwiserotation of drum 40 and contact between tang 56 and wall 23 with resulting space between tang 5 8anid wall 25. This is clearly shown in FIGURE 7. Further axial loading in either direction is increasingly resisted'by the action of the coil brake.

To release coil 54 from its gripping action on drum 40, it is only necessary to spread tangs 56, 58 to increase the inside diameter of the coils. On e the coil inside diameter isincreased to or beyond that of the drum, braking action therebetween is released. 7

A release mechanism for the coil is shown in FIG- URES 3, 4 and 5. Cover '70, which carries the release mechanism, is adapted to be secured on outer casing 12. More specifically, a dependent tab 72 on one end of the cover is adapted to be received in slot 22' in interlocked relationship therewith. The other end of cover 70 is secured in place on casing 12 by screw 74adapted to be threaded therein. A lever or hell crank '7-5 is pivotally carried on the underneath of cover 70 and is adapted to be manipulated by bellows 76 for spreading tangs 56, 58 of coil brake 54. Lever 75 is pivotally carried on pin or stud 78 for movement thereabout. The lever configuration in plan view is clearly shown in FIGURE 3. It includes an arm 79 which terminates in a flat portion 80 adjacent expansible. bellows 76. Pressure applied upon expansion of the. bellows is adapted to turn lever '75 counterclockwise, as viewed in FIGURE 3. A central portion of the lever received on pin 78 includes oppositely disposed depending side portions or tabs S1 and 82. The tabs are mostclearly shown in the partially cut-away side view in FIGURE 5. Tabs 81 and 82 are disposed between and adjacent tangs 56 and 58, respectively, of coil brake 54.

Bellows 7 6 are connected through a flexible hose 83 to a compressible bulb 84. The bulb is adapted to be so disposed that a chair or bed occupant can manually collapse it to expel air into bellows 76 for operating the release mechanism.

FIGURE 3 shows bellows 76 collapsed and lever 75 in a relaxed position. In other words, tabs 81 and 82 of the lever are not being urged to spread tangs 56, 58. In this position of the lever, coil brake 54 grips drum 40 with the tangs positioned to move into contact with the side walls of slot 22 upon initial rotation of the drum. The position-holding device is braked or maintained in a preselected relative position. FIGURE 4 shows bellows 76 expanded to urge lever counterclockwise about pin 78. In this position, coil brake 54 is released from drum .40 by reason of tabs 81 and 82 on lever 75 expanding tabs 56 and 58. With lever 75 in the position of FIGURE 4, drum 40 is free for rotation in either direction which permits the inner or extensible casing 16 to be freely moved to a new position relative to casing 12. Once again, release of pressure exerted by bellows 76 permits coil brake 54 to grip drum 40 and prevent its rotation for further expansion or retraction of extensible casing 16 within outer casing 12.

The extent to which it is necessary to expand tangs 55 and 58 to loosen the grip of coil brake 54 does not exceed the wall-to-wall dimension of slot 22. The normal resiliency of coil brake 54 returns lever 75 to a noninterfering position (FIGURE 3) upon collapse of bellows 7 6.

It is to be understood that other mechanical means, or a solenoid, could be used to manipulate lever 75.

In a sense, tangs 56, 58 of coil brake 54, may be considered as floating within slot 22. That is, in normal operation, they are adapted to move from contact with one wall to the other of slot 22, depending upon the direction of load. Also, the tangs are adapted to be spread within the confines of slot 22 for releasing coil 54 from drum 40 whenever anew holding position is required.

A protective cover .86, which may be of elastic material, is adapted to be removably secured on the inner end of casing 12.

It is readily apparent by the drawings and this specification that an improved position-retaining device has been disclosed which is capable of retaining any preselected relative position of bodies against load for use on chairs having reclining backs, hospital beds or the like. The internal braking mechanism is adapted to hold the device in a preselected position against relative linear movement in either direction. Manipulation of lever 75 causes release of the coil brake to permit a new position of the back rest or bed to be selected.

Having thus described our invention, it is obvious that various modifications may be made in the same without departing from the spirit of the invention; and, therefore, We do not wish to be understood as limiting ourselves to the exact forms, constructions arrangements and cornbinations of parts herein shown and described.

We claim:

1. A mechanical position-retaining device comprising in combination:

a first portion having means for attachment to a positionable member,

a second portion rectilinearly movable relativeto the first portion and having means for attachment to a second positionable member,

one of said portions having a fixed nut and the other of said portions rotatably carrying a rod having threading for cooperation with said nut,

said: rod and nut threading being relatively steep so that an axial force applied nectilinearly between said first portion and said second portion tends to rotate said rod,

coiled resilient means encircling a portion of said rod and normally holdingly engaging said portion,

saidcoiled resilient means having terminal portions disposed between spaced stops on said other portion so that a force tending to rotate said rod in either direction urges one of said terminal portions against a respective stop for increased holding engagement between said coiled resilient means and said rod portion to prevent rotation of said rod and relative rectilinear movement between said first portion and said second portion,

and means for selectively releasing said holding engagement of said coiled resilient means on said rod portion so as to permit relative rotation therebetween and rectilinear movement in either direction between said first portion and said second portion.

2. In a mechanical position-retaining device including,

a first portion having means for attachment to a positionable member,

a second portion recilinearly movable relative to the first portion and having means for attachment to a second positionable member,

one of said portions having a fixed nut and the other of said portions rotatably carrying a rod having threading for cooperation with said nut,

said threading on said rod and nut being relatively steep so that an axial force applied rectilinearly between said first portion and said second portion tends to rotate said screw,

the improvement comprising:

helical brake means encircling and normally engaging a portion of said rod,

said helical brake means including at least a pair of tangs thereon floatingly disposed between spaced apart stops on said other portion whereby rotation of said rod in. either direction is braked by said helical brake whenever a tank is urged against a respective one of said stops so as to prevent relative rectilinear movement between said first portion and said second portion,

and means for spreading said tangs so as to permit rotation of said rod and relative rectilinear movement in either direction between said first portion and said second portion.

3. A mechanical position-retaining device comprising in combination:

a first section having means for attachment to a positionable member.

a second section rectilinearly movable relative to the first section and having means for attachment to a second positionable member,

one of said sections having a fixed threaded part and the other of said sections rotatably carrying a threaded part having threading for coopertaion with said fixed threaded part,

said threading being relatively steep so that an axial force applied rectilinearly between said first section and said second section tends to rotate said rotatable threaded part,

locking means cooperable with a portion of said rotatable threaded part and normally holdingly engaging said portion,

said locking means including activating means so dis posed that rotation of said rotatable threaded part in either direction urges said activating means for increased holding engagement between said locking means and said rotatable threaded part portion to prevent rotation thereof and relative rectilinear movement between said first section and said second section, and means for selectively releasing said holding engagement of said locking means on said rotatable threaded part portion so as to permit relative rotation therebetween and rectilinear movement in either direction between said first section and said second section.

4. A mechanical position-retaining device comprising in combination:

a first section having means for attachment to a positionable member, a second section rectilinearly movable relative to the first section and having means for attachment to a second positionable member, I

one of said sections having a fixed threaded part and the other of said sections rotatably carrying a threaded part having threading for cooperation with said fixed threaded part,

said threading being relatively steep so that an axial force applied rectilinearly between said first section and said second section tends to rotate said rotatable threaded part,

locking means cooperable with a portion of said rotatable threaded part and normally holdingly engaging said portion,

said locking means having a pair of abutments cooperable with engagement means and so disposed that rotation of said rotatable threaded part in either di rection urges one of said abutments into engagement with said engagement means for increased holding engagement between said locking means and said rotatable threaded part portion to prevent rotation thereof and relative rectilinear movement between said first section and said second section,

and means for selectively releasing said holding engagement of said locking means on said rotatable threaded part portion so as to permit relative rotation therebetween and rectilinear movement in either direction between said first section and said second section.

5. A mechanical position-retaining device comprising in combination:

a first section having means for attachment to a positionable member,

a second section rectilinearly movable relative to the first section and having means for attachment to a second positionable member,

one of said sections having a fixed threaded part and the other of said sections rotatably carrying a threaded part having threading for cooperation with said fixed threaded part,

said threading being relatively steep so that an axial force applied rectilinearly between said first section and said second section tends to rotate said rotatable threaded part,

locking means comprising a coiled member cooperable with a portion of said rotatable threaded part and normally holdingly engaging said portion,

said coiled member including projecting abutment means cooperable with one of said sections and so disposed that rotation of said rotatable threaded part in either direction urges said abutment means into engagement with said section for increased holding engagement between said locking means and said rotatable threaded part portion to prevent rotation thereof and relative rectilinear movement between said first section and said second section,

and means for selectively releasing said holding engagement of said locking means on said rotatable threaded part portion so as to permit relative rotation therebetween and rectilinear movement in either direction between said first said section and said second section.

6. A mechanical position-retaining device comprising in combination:

a first portion having means for attachment to a positionable member,

a second portion rectilinearly movable relative to the first portion and having means for attachment to a second positionable member,

one of said portions having a fixed nut and the other of said portions rotatably carrying a rod having threading for cooperation with said nut such that an axial force applied rectilinearly to one of said portions tends to rotate said rod,

i frictional means operative to normally lightly engage a portion of said rod and to hold-ingly engage said portion,

said frictional means having parts disposed between 10 said first portion and said second portion,

' and means for selectively releasing engagement of said frictional means on said rod portion so as to permit relative rotation therebetween and rectilinear movement in either direction between said first portion and 15 said second portion.

References Cited by the Examiner UNITED STATES PATENTS 6/1950 Huck 18882.3 X 12/ 1951 Cushman 297-361 9/1952 Rauten 188-140 X 6/1956 Howell 297375 7/ 1962 Martens 297-361 11/ 1962 Hanizeski 18877 12/1963 Butler 18873 FOREIGN PATENTS 12/ 1950 Germany. 4/ 1951 Germany. 8/ 1960 Great Britain.

CLAUDE A. LE ROY, Primary Examiner. 

1. A MECHANICAL POSITION-RETAINING DEVICE COMPRISING IN COMBINATION: A FIRST PORTION HAVING MEANS FOR ATTACHMENT TO A POSITIONABLE MEMBER, A SECOND PORTION RECTILINEARLY MOVABLE RELATIVE TO THE FIRST PORTION AND HAVING MEANS FOR ATTACHMENT TO A SECOND POSITIONABLE MEMBER, ONE OF SAID PORTIONS HAVING A FIXED NUT AND THE OTHER OF SAID PORTIONS ROTATABLY CARRYING A ROD HAVING THREADING FOR COOPERATION WITH SAID NUT, SAID ROD AND NUT THREADING BEING RELATIVELY STEEP SO THAT AN AXIAL FORCE APPLIED RECTILINEARLY BETWEEN SAID FIRST PORTION AND SAID SECOND PORTION TENDS TO ROTATE SAID ROD, COILED RESILIENT MEANS ENCIRCLING A PORTION OF SAID ROD AND NORMALLY HOLDINGLY ENGAGING SAID PORTION, SAID COILED RESILIENT MEANS HAVING TERMINAL PORTIONS DISPOSED BETWEEN SPACED STOPS ON SAID OTHER PORTION SO THAT A FORCE TENDING TO ROTATE SAID ROD IN EITHER DIRECTION URGES ONE OF SAID TERMINAL PORTIONS AGAINST A RESPECTIVE STOP FOR INCREASED HOLDING ENGAGEMENT BETWEEN SAID COILED RESILIENT MEANS AND SAID ROD PORTION TO PREVENT ROTATION OF SAID ROD AND RELATIVE RECTILINEAR MOVEMENT BETWEEN SAID FIRST PORTION AND SAID SECOND PORTION, AND MEANS FOR SELECTIVELY RELEASING SAID HOLDING ENGAGEMENT OF SAID COILED RESILIENT MEANS ON SAID ROD PORTION SO AS TO PERMIT RELATIVE ROTATION THEREBETWEEN AND RECTILINEAR MOVEMENT IN EITHER DIRECTION BETWEEN SAID FIRST PORTION AND SAID SECOND PORTION. 